Mopar Muscle magazine did a test on a series of these kits. They tested on an LX Charger or a LC Challenger. The cheapest kit actually made the most HP gain. The brand was Spectre. It looked sorta cheap compared to the others but it performad best. I don't recall the specifics but it did add just shy of 18 HP to the rear wheels.
I added a K and N jit to my 2007 Ram when it was new. It mostly increased the sound. I don't know if adding 18 HP to a 5000 pound truck could be felt. Sorta like a 500 pound woman losing 10 pounds...sorta hard to notice.
NO, my wife is not fat.